**Trader consensus strongly favors a 19°C minimum in Tokyo on September 27, 2026, reflecting model consensus and real-time observations of mild overnight conditions.** Persistent cloud cover, high humidity near 85–90%, and light northerly winds have limited radiative cooling, keeping temperatures from falling below the seasonal baseline. Official forecasts from multiple sources indicate the overnight low stabilizing around 18–20°C, with hourly readings holding near or above 19°C amid overcast skies and scattered light rain. This aligns with typical late-September climatology for the region, where minimums average near 19°C. A clear-sky break or stronger radiational cooling could push readings to 18°C or lower, though current model agreement and atmospheric moisture make that outcome unlikely before midnight resolution.